Self-valving web loading and transportation

ABSTRACT

In a single capstan two-vacuum chamber web transport, the web (tape) is vacuum urged into the chambers. The web has a tendency to slip over the capstan such that one chamber receives all of the tape to the exclusion of the other. This undesired action is prevented by providing fluid communication means extending between the two chambers with no other fluid communication connections. As the web enters one chamber, it is clamped to the fluid communication means by the vacuum applied through the other chamber. Movement of the web over the capstan is then inhibited, and the web loads into the other chamber. When the web is in both chambers, the fluid communication means is sealed off by the web making it inoperative.

o m it t v llnte n51 memo lmiclltinson et al., Feb. 29, R972 [54]@ELlF-VALVIING WEB LUADIING AND 3,187,971 6/1965 Miller et a1 ..242/182X TRANSPURTATHON 3,254,854 6/1966 Deighton et al ..242/182 X [72]lnventors: William lll. Dickinson, Boulder; John W. primary Examine,.(;eorge F Mautz Longmom, both of Colo- Attorney-Hanifin and Jancin andHerbert F. Somermeyer [73] Assignee: international Business MachinesCorporatint], Armonk, N.Y. [571 ABSTRACT [22] Filed; Jam 29 1970 In asingle capstan two-vacuum chamber web transport, the web (tape) isvacuum urged into the chambers. The web has a 1 PP 6,815 tendency toslip over the capstan such that one chamber receives all of the tape tothe exclusion of the other. This undesired action is prevented byproviding fluid communication '5' means extending between the twochambers with no other [58] Mei! 242/182 184 fluid communicationconnections. As the web enters one I chamber, it is clamped to the fluidcommunication means by the vacuum applied through the other chamber.Movement of the web over the capstan is then inhibited, and the webloads [56] References Cited into the other chamber. When the web is inboth chambers, UNlTED STATES PATENTS the fluid communication means issealed off by the web making it inoperative. 3,122,332 2/1964 Hughes, Jr..242/184 3,148,816 9/1964 Martin et al. ..226/118 X 7 Claims, 3 DrawingFigures SOURCE I Patented Fb.29, 1912 3,645,470

FIG. 1

FIG. 3:

INVEIIWRS IILLIMI H. DIOKINSW JOHN I. IRIIII ATTORNEY SELF-VALVING WEBLOADING AND TRANSFUIITA'IIGN BACKGROUND OF THE INVENTION This inventionrelates to web transport and, more particularly, to apparatus whichfacilitates loading a web into vacuum chambers (for example of the typeincluded in FatentOfflce classification 242-182).

In present day single capstan magnetic tape handlers or drives, relianceis placed upon the wrap of the tape around the capstan and the pull ofthe vacuum in the adjacent vacuum columns or storage chambers to preventthe tape from slipping over the capstan. While loading the tape, vacuumis applied to the chambers and the storage reel brakes are released toallow the tape to be drawn into the vacuum chambers. At this time, theweb or tape can easily load into one column first to the exclusion ofthe other column. That is, in loading, the web extends between twosupply spools over the web-receiving openings in the chambers. Thespools are freed for rotation to permit web unspooling into thechambers. The frictional engagement of the capstan with the web isrelied upon to prevent the web from a spool to move past the opening ofan adjacent chamber over the capstan and thence into the chamberreceiving web from the other spool. When this happens, no part of theweb enters the adjacent chamber. This undesired action is caused by thetape slipping over the capstan (i.e., the wrap of the web on the capstanis insufficient to prevent it from slipping thereover). With the reelbrakes released, no tension is applied to the tape resulting in a lowfrictional engagement with the capstan. If the tape or web loads intoone chamber to the exclusion of the other, not only is there possibletape damage, but human intervention is required to restore normaloperation. Ideally, the web loads equally into both vacuum chambers;however, due to variations in the web caused by extended storage in tapelibraries, creased tape, friction, and unexplainable friction in thetape path between the spools and the chambers, the tape or web sometimeswill load into one chamber and not load into the other. In dataprocessing operations, this is called tape dump requiring manualintervention. The web will not enter a second vacuum chamber because itthen extends over the opening of the chamber with the vacuum or fluidflow in the chamber insufficient to cause it to load into such chamber.

SUMMARY OF THE INVENTION It is an object of this invention to provide aweb-handling device which loads a web into two web-receiving vacuumchambers in a manner that the web is not loaded entirely into onechamber to the exclusion of the other chamber.

Apparatus using the present invention includes a pair of vacuumchambers, preferably in a side-by-side relationship. Each chamber has aweb-receiving opening at the same end of a common wall separating thechambers. A web-moving capstan is rotatably disposed on that same end ofthe wall between the openings. Fluid communication means extend betweenthe chambers immediately below the capstan such that the vacuum in thetwo chambers is exchanged through such fluid communication means. Whenloading a web, when the web first enters the first chamber, the web isclamped to the fluid communication means by the vacuum from the otherchamber. The web then cannot slide over the capstan into the firstchamber. The web then proceeds to load into both chambers. When the webis covering both ends of the fluid communication means in the respectivechambers, the fluid communication means is inoperative to affect webmotion. In the illustrated embodiment, the fluid communication means hasa dimension less than the thickness of the wall, which corresponds tothe width of the web being handled. In one preferred embodiment, fluidcommunication means comprises a plurality of apertures extending throughthe wall. The apertures are preferably chamfered at the end to preventweb wear. In another embodiment, the fluid communication means comprisesa slot formed in the front side of the common wall between the chambers.The fluid communication means is completed by a door, which is movableagainst thefront face of the wall to close the slot to form aehannelbetween the two web-receiving chambers. It is preferred that acommon vacuum source provide vacuum to'both ofthe web-receivingchambers.

The foregoing and other objects,teatures, and advantages of theinvention will be apparent from thefollowing'more particular descriptionof preferred embodiments of the invention. as illustrated in theaccompanying drawings.

DESCRIPTION OF TIIEDRAWINGS FIG. 1 is a simplified diagrammatic frontcross-sectional view of an apparatus incorporating; the teachings of thepresent invention.

FIG. 2 is a simplified cross sectional diagrammatic view of a slot-typeof fluid communication means usable with the FIG. I illustratedapparatus.

FIG. 3 is a simplified diagrammatic representation of another fluidcommunication means comprising a single hole extending through a walland usable with the FIG. I illustrated apparatus.

DETAILED DESCRIPTION With particular reference to the drawings, *likenumbers indicate like parts and structural features in the three views.In FIG. 1, a pair of tape or web supply spools III and II are disposedon opposite sides of the pair of web-receiving vacuum chambers 13 and14. Common wall 15 is intermediate the web-receiving chambers and formsone side of each chamber. Rotatably disposed on the upper end of wall 15is web-driving capstan I6 used to transport web 19 between web-receivingchambers 13 and M. Common wall I5 has web contacting surfaces in thechambers. Vacuum source I7 is in fluid communicative relationship tocommon plenum 18 which forms the bottom portion of web receivingchambers I3 and Id. In operation, source 17 provides an equal vacuum toboth chambers I3 and I4 such that web 19 has an equal force exertedthereon at theweb receiving openings 20 and ZI of the chambers. Thewidth of web I9 approximates the depth of chambers I3 and I4 and, hence,the width of web-contacting surfaces 46 and 4-7, as measuredperpendicular to the face of the drawing.

To load web I9 into chambers 13 and 14, web 19 is moved across theoutside of openings 20, 21, and across capstan I6, as indicated bydotted line 25. The motors or brakes of spools It) and I2 are releasedsuch that web I9 is free to unreel from both spools. Vacuum spool 17 isactivated to provide a vacuum in both chambers I3 and I4. The resultingpressure differential across web I9 urges it downwardly into chambers I3and 14, as is well known. In prior web handling devices, the wrap of web19 on the friction surface of capstan I6 was relied upon to prevent theweb from moving therea'cross. That is, when spools 10 and II are freedfor rotation, very little friction exists between web I9 and capstan Id.In this situation, web leaving spool 10 can slide over capstan 16 intochamber Id with no web entering chamber I3. In magnetic tape handlers,this undesired action causes an inoperative situation requiring manualintervention.

The present invention teaches a modification of the abovedescribed tapehandler to prevent this untenable situation from occurring. Chambers 13and Id have a depth approximately equal to the width of web I9 and, assuch, the pressure differential provided by vacuum source I7 makes theweb appear as a piston causing it to enter the two chambers. Accordingto the present invention, in addition to this piston effect, web I9 isalso used as a valve during loading.

According to this invention, a fluid communication means extends throughcommon wall 15 providing fluid communication between chambers I3 and 14.In FIG. I, the fluid communication means comprises a pair of holes 30extending through wall 15 immediately below capstan I6 and abovemagnetic transducer 31. No other fluid communication connections aremade to tubes 30. In some prior art configurations, a vacuum source wasconnected to tubes extending between the two vacuum chambers. However,the extra connection decoupled the fluid communication connectionbetween chambers 13 and 14 and made such connections ineffective toprovide the now-described valving operation in accordance with thepractice of the present invention.

The combination of fluid communication means 30 and web 19 creates avalve for temporarily clamping web 19 against common wall 15 duringloading operations such that the web 19 loads equally into both chambers13 and 14. Assume, for purposes of discussion, that web 19 has loaded,as indicated by the solid line extending through chambers 13 and 14. Atthis time, the web 19 is pulled by vacuum from chamber 13 against commonwall 15, as at 32. Since web 19 has a width equal to the depth of wall15, and the holes 30 are less than the depth of wall 15, the web 19blocks the vacuum flow between chambers 13 and 14. Web 19 no longer canslide over capstan 16 from spool into chamber 14. The vacuum source thenpulls web 19 into chamber 13 at least until it reaches the positionindicated by dotted line 33. At this time, web 19 covers both ends oftubes 30, thereby removing the vacuum therefrom making it inoperative toclamp web 19 in either chamber. It is understood that web 19 may beloaded further into chambers 13 and 14, as may be desired.

During subsequent web handling operations, such as in a magnetictransducing operation (reading or writing), web 19 is kept in chambers13 and 14 such that it always covers both ends of tubes 30. When thisarrangement is maintained, tubes 30 are inoperative to affect movementof web 19.

Also of interest is the possibility of the web being removed fromchamber 13 during web-handling operations. If this is the case, web 19is again clamped against the wall at area 32. If the reel 10 isactivated to move web 19 toward capstan 16, the vacuum provided bysource 17 may again reload web 19 into chamber 13, as above described.

In FIG. 2, a modification of the fluid communication means is shown. Inthis arrangement, slot 40 is formed in the front face 41 of common wall15. Relating to FIG. 1, common wall face 41 is facing the viewer of thedrawing. In this instance, a glass door 42 is hingedly secured to oneside of the vacuum columns, such as at 43. During normal operation, door42 is closed against the FIG. 1 illustrated assembly to completeweb-receiving chambers 13 and 14, as is well known, and, as well, toclose slot 40 to provide a fluid communication means extending betweenchambers 13 and 14.

In FIG. 3, single hole 44 is shown as constituting fluid communicationmeans. This hole extends to the web-receiving chamber walls 45 and 46without recess 47 illustrated in FIG. 1. It is understood that any formof fluid communication means may be provided so long as they extendbetween the chambers relatively close to capstan 16; that is, such thatduring normal web handling operations, the web always covers both endsof the fluid communication means.

If common wall 15 were an extremely thin wall, the fluid communicationmeans could be a set of perforations extending through the wall. Asshown in FIG. 1, transducer 31 is below fluid communication means 30.Since, in a magnetic tape handling operation, the transducer must be incontinuous operative relationship to web or tape 19, it is seen that thefluid communication means will always be covered by the web duringtransducing operations. No limitation to the placement of the fluidcommunication means is intended. It could also be placed belowtransducer 31.

The fluid communication means need not extend directly between chambers,such as shown in FIG. 1. Altemately, the fluid communication withchamber 13 may be lower than in chamber 14, such as below transducer 31,or vice versa. Depending upon the type of loading and other designfactors, the fluid communication between chambers 13 and 14 may beestablished for loading control in a myriad of configurations. Also, asused herein, the term intermediate is intended to include connectionsmade between chambers 13 and 14 either through common wall 15 or via aC-shaped conduit extending outwardly from web contacting surfaces 50 and51, respectively, in chambers 13 and 14, that is, a fluid passagewayopening through surfaces 50 and 51 and with no other openings.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is: 1. A web-handling device for a single elongated web,including in combination:

means defining first and second adjacent web-receiving chambers andhaving web-contacting surfaces, each chamber having a web-receivingopening for the web and a fluid therein,

web path means establishing a travel path between said chambers for theweb receivable by both said chambers,

pneumatic means in communicative relation with said chambers exhaustingfluid therefrom such that said chambers have a lower pressure insidethan outside said chambers, and

fluid communication means in said means defining said chambers forproviding fluid communication between said chambers and only havingopenings through said web-contacting surfaces.

2. The device set forth in claim 1 wherein said web path means furtherincludes a rotatable web-transporting member between said web-receivingopenings, and having a web-engaging surface for frictionally engaging aweb during loading such that web movement thereacross is somewhatinhibited but sliding movement of said web over said member possiblyoccurring at low web tensions, said web entering said chambers by saidfluid exhaustion, such entry being subject to variations including entryof one chamber to the exclusion of the other chamber, said fluid exhaustfrom said other chamber acting through said fluid communication means toclamp said web to said fluid communication opening in said one chamberto inhibit further entry of said web thereinto and thereby facilitatingentry of said web into said other chamber, and said fluid communicationmeans inhibiting movement of said web over said member until the web hasloaded into both chambers a predetermined amount, as determined by saidfluid communication opening in said one chamber, at which time said webblocks said fluid communication means in both chambers to make itinactive.

3. A magnetic tape transport having the device set forth in claim 2 andfurther including a transducer in said first chamber, and

said fluid communication means establishing fluid communication fromsaid second chamber to said first chamber intermediate said transducerand said web transporting member.

4. The transport set forth in claim 3 wherein said pneumatic means has acommon communicative relation with said first and second chambersopposite said web-receiving openings such that both chambers havesubstantially the same lowered pressure therein.

5. The device of claim 2 with a common wall separating said chambers andwherein the chambers have a depth substantially equal to the width ofthe web to be received with the chamber depth extending along saidcommon wall,

said fluid communication means having a dimension not greater than saidweb width along said web contacting surfaces in each chamber, andextending through said common wall.

6. The device of claim 5 wherein said fluid communication openingcomprises a slot extending through said common wall between saidweb-contacting surfaces and further having a door closable against saidcommon wall over said slot.

7. The method of loading an elongated web into first and second adjacentweb-receiving chambers respectively having b first and second webcontacting surfaces, the improvement inthe second chamber whenever saidweb has entered the cluding the following steps in combination: firstchamber a first distance and has not entered the disposing an elongatedweb across web-receiving openings second chamber along said second webcontacting surof said chambers, face a second distance for clamping theweb against providing a pressure differential across said web for urging5 fuftl'lfil' movemflm into Said firs! chambfif, n I

sameimo Said Chambers, removing said clamp when the web has loaded intosaid establishing a vacuum clamp in said first chamber along said Secondchambu 531d second dlsmncefirst web contacting surface dependent uponpressure in t

1. A web-handling device for a single elongated web, including incombination: means defining first and second adjacent web-receivingchambers and having web-contacting surfaces, each chamber having awebreceiving opening for the web and a fluid therein, web path meansestablishing a travel path between said chambers for the web receivableby both said chambers, pneumatic means in communicative relation withsaid chambers exhausting fluid therefrom such that said chambers have alower pressure inside than outside said chambers, and fluidcommunication means in said means defining said chambers for providingfluid communication between said chambers and only having openingsthrough said web-contacting surfaces.
 2. The device set forth in claim 1wherein said web path means further includes a rotatableweb-transporting member between said web-receiving openings, and havinga web-engaging surface for frictionally engaging a web during loadingsuch that web movement thereacross is somewhat inhibited but slidingmovement of said web over said member possibly occurring at low webtensions, said web entering said chambers by said fluid exhaustion, suchentry being subject to variations including entry of one chamber to theexclusion of the other chamber, said fluid exhaust from said otherchamber acting through said fluid communication means to clamp said webto said fluid communication opening in said one chamber to inhibitfurther entry of said web thereinto and thereby facilitating entry ofsaid web into said other chamber, and said fluid communication meansinhibiting movement of said web over said member until the web hasloaded into both chambers a predetermined amount, as determined by saidfluid communication opening in said one chamber, at which time said webblocks said fluid communication means in both chambers to make itinactive.
 3. A magnetic tape transport having the device set forth inclaim 2 and further including a transducer in said first chamber, andsaid fluid communication means establishing fluid communication fromsaid second chamber to said first chamber intermediate said transducerand said web transporting member.
 4. The transport set forth in claim 3wherein said pneumatic means has a common communicative relation withsaid first and second chambers opposite said web-receiving openings suchthat both chambers have substantially the same lowered pressure therein.5. The device of claim 2 with a common wall separating said chambers andwherein the chambers have a depth substantially equal to the width ofthe web to be received with the chamber depth extending along saidcommon wall, said fluid communication means having a dimension notgreater than said web width along said web contacting surfaces in eachchamber, and extending through said common wall.
 6. The device of claim5 wherein said fluid communication opening comprises a slot extendingthrough said common wall between said web-contacting surfaces andfurther having a door closable against said common wall over said slot.7. The method of loading an elongated web into first and second adjacentweb-receiving chambers respectively having first and second webcontacting surfaces, the improvement including the following steps incombination: disposing an elongated web across web-receiving openings ofsaid chambers, providing a pressure differential across said web forurging same into said chambers, establishing a vacuum clamp in saidfirst chamber along said first web contacting surface dependent uponpressure in the second chamber whenever said web has entered the firstchamber a first distance and has not entered the second chamber alongsaid second web contacting surface a second distance for clamping theweb against further movement into said first chamber, and removing saidclamp when the web has loaded into said second chamber said seconddistance.